THREE-COMPONENT CONDENSATION OF CYCLIC 1,3-DICARBONYL COMPOUNDS, N-PHENACYLPYRIDINIUM SALTS, AND ISATINS OR AROMATIC ALDEHYDES AS A METHOD FOR THE SYNTHESIS OF NOVEL CONDENSED 2-AROYL-2,3-DIHYDROFURANS

Abstract

Three-component condensation of in situ generated pyridinium aroylmethylides with isatins or aromatic aldehydes and cyclic 1,3-dicarbonyl compounds gave a series of condensed 2-aroyl-2,3-dihydrofurans. The reaction proceeds diastereoselectively and represents a cascade process involving the Knoevenagel condensation, the carbo-Michael reaction, and intramolecular nucleophilic substitution. The possibility of reductive rearrangement of spirocyclic furanyl-substituted oxindole into a pyran derivative by the action of zinc in acetic acid was shown.